ABSTRACT
Ill-defined problems present a dilemma for planning: how can one plan the route towards a solution if one knows so little about the path ahead, especially when one does not know the final destination or goal state. Puzzles such as the nine-dot and radiation problems (illustrated in Figure 3.1 and Box 3.1,
respectively) are considered ill-defined because components of their problem spaces are not fully specified. In particular, the problem descriptions lack a statement of a concrete and visualizable goal state. Heuristics that evaluate the progress made towards a goal state are not obviously applicable to solving ill-defined problems, because it is difficult to describe a test for the final state that could be used in evaluating progress (VanLehn, 1989). However, faced with an ill-defined problem, individuals can and do plan. In fact, planning is central to both failure and success at solving ill-defined problems. Moreover, planning lies at the heart of commonalities among expert problem solvers.
